The subject matter disclosed herein relates to fluid couplings and, in particular, to valves and valve technology.
Many valves use a cylinder, a piston, a disc, and a nozzle that work together to regulate flow of a working fluid. Pilot-operated valves also include a pilot assembly that can utilize the working fluid to generate force on the piston. This force can effect contact of the disc with the nozzle. Pilot-operated valves may further incorporate one or more o-rings that create a seal between the periphery of the piston and the inner wall of the cylinder. This seal allows the cylinder to pressurize to generate the downward force that moves the piston to position the disc in contact with the nozzle.
Depending on the application, pilot-operated valves may experience a wide range of operating conditions. For example, liquefied gas is often kept at temperatures of −320° F. On the other end of the temperature spectrum, pressurized steam can reach temperatures of 750° F. or greater. Unfortunately, the o-rings found in pilot-operated valves (and other types of valves) are often made of materials (e.g., elastomeric materials and/or plastic) that are not compatible with these extreme operating temperatures.
To avoid unnecessary breakdown of the o-rings, one solution is to condition the working fluid before the working fluid enters the cylinder. For example, the valve may incorporate a heat exchanger that can cool or heat the working fluid to appropriate temperatures before the working fluid enters the cylinder. Another solution is to design the valve to operate without the o-ring. These designs may utilize seals that form from metal-to-metal contact, e.g., between the piston and the cylinder. However, manufacturing tolerances and other mechanical changes in the valve can disrupt contact between components of the valve and, thus, render the seals and the valve ineffective.